OBJECTIVETo establish the comparative proteomic profiles of retinoid acid (RA) resistant human acute promyelocytic leukemia (APL) NB4-R1 cells before and after apoptosis induced by realgar (tetra-arsenic tetra-sulfide, As4S4).

METHODSFirst a serial of assays were performed using MTT, transmission electron microscopy, Annexin V FITC/PI double-stain, flow cytometry and confocal laser scanning microscopy to qualitatively and quantitatively observe the in vitro apoptosis inducing effect of realgar on RA-resistant cells. Then the comparative proteomic profile before and after NB4-R1 apoptosis was established using high-resolution two-dimensional electrophoresis system.

RESULTSThe inhibition effect of realgar on NB4-R1 cell growth was dose and time dependent. The 24-h 50% inhibiting concentration (IC50) was 24.06 +/- 0.19 micromol/L, and the 48-h IC50 9.50 +/- 0.13 micromol/L, and 72-h IC50 6.55 +/- 0.03 micromol/L, respectively. 24 h and 48 h were the early and late phase of major NB4-R1 apoptotic cell populations induced by 25 micromol/L realgar respectively. Differential proteomic profiles before and after realgar induced NB4-R1 apoptosis were successfully established. Averagely 1069, 975 and 893 spots could be detected of the untreated group (R0), the 24-h treatment group (R24), and the 48-h treatment group (R48), respectively by ImageMaster 2D Platinum Software. The matching rate between R24 and R0 was 79.94% and that between R48 and R0 69.33%, and that between R24 and R48 71.91%.

CONCLUSIONDifferential proteomic profiles of realgar induced NB4-R1 apoptosis were successfully established for the first time, which provided a basis for comprehensively understanding the signal transduction of realgar induced apoptosis in RA-resistant APL cells, also for screening new bio-markers and drug targets of hematopoietic malignant tumor.